Sulfur Cinquefoil (Potentilla Recta) Identification and Control CPOP Listserv Discussion

Information and photos to identify sulfur cinquefoil (Potentilla recta), especially to distinguish P. recta from the native P. gracilis. Some control methods are also discussed.

Summary

In June of 2014, several CPOP Listserv contributors discussed various tips and tricks to identify and treat sulfur cinquefoil (Potentilla recta), an invasive forb that looks similar to the native slender cinquefoil (Potentilla gracilis). Contributors agreed that one of the biggest identifying differences between the two plants was the underside of the leaves: where P. recta is green on the underside, almost the same color of green as the top of the leaves, P. gracilis has a white or white-silver underside. It was noted however, that in other regions this characteristic may not be reliable for identification, and other characteristics may need to be used to differentiate between the two species.

Further identification information can be P. gracilis P. recta found in Flora of the Pacific Northwest by Leaves White to silver-white Green underside, Hitchcock and Cronquist. See additional undersides almost as green as comparison photos at the end of this top document. Other photos and additional Flowers Bright yellow flowers Pale yellow flowers identification information can be found at Flower bracts Bracts noticeable Bracts same length smaller than sepals as sepals the University of Washington Burke Seeds Smooth surface Reticulate (veiny) Museum website as well surface (http://biology.burke.washington.edu/herb arium/imagecollection.php).

Suggestions for control

Nate Johnson offered up his control methods for P. recta, noting that they were very labor intensive, using extensive surveys to locate new populations and man-power to treat known areas. Johnson emphasized the importance of surveying. Each year they locate new small population this way. Johnson typically uses 2-3% Garlon 3A with 0.25% nufilm surfactant and 1% marking dye.

Rod Gilbert stressed the importance of pulling the flower heads if P. recta is in bloom because the plant will still go to seed even if sprayed at that point. He also suggested recording GPS locations of plants so that they can be relocated in the spring when they are more susceptible to control methods. Photo credit Bruce Newhouse. Comparison of the upper and lower leaves of P. recta and P. gracilis.

Sulfur Cinquefoil (Potentilla recta) Identification and Control 1 Sulfur Cinquefoil Identification Original CPOP Listserv Messages

The CPOP Listserv Archive can be found for subscribers at listserv.wa.gov. To subscribe to the CPOP Listserv visit our website at cascadiaprairieoak.org.

June 4, 2014 – Nathan Johnson (Center for Natural Lands Management)

Sulfur cinquefoil (Potentilla recta) is a serious threat to native grasslands and prairies in our ecoregion. The attached pictures show a very dense 1/10 acre infestation just detected on Joint Base Lewis McChord (JBLM). If you zoom into the foreground you can make out thousands of erect stems with deeply loped leaves and flower buds at the top. The crew in the background are treating plants that are just as dense as the foreground. It is growing in with tall oat grass (another prairie invader). We have many small populations of sulfur cinquefoil across JBLM that we have been controlling for years. This population was previously unknown and clearly demonstrates the invasive potential of this plant if left unchecked.

Be careful not to confuse this plant with our native Potentilla gracilis which has a silvery-white underside to the leaf.

Nathan Johnson Invasive Species Project Manager Center for Natural Lands Management

June 4, 2014 – Bruce Newhouse

Greetings!

I'd like to add to that a bit.

There are comparison photos available at: http://brucen.zenfolio.com/p766205970 Click "Show All" and scroll about half way down. File names show when you click on them individually, and they are in alpha order. I think #168 particularly is useful.

The Potentilla gracilis var. gracilis I'm familiar with in the southern Willamette Valley is pale to almost white and hairy underneath (but not silver) - giving a distinct two-tone contrast of the upper leaf surface versus the lower. Potentilla recta leaf undersides are nearly as green as the leaf upperside. Hitchcock and Cronquist's Flora of the PNW (1973) lists some additional differences. (More in the 5-volume Flora of the PNW if you have access to it.)

Also, the Burke Herbarium at UW has lots of photos of both: http://biology.burke.washington.edu/herbarium/imagecollection.php

It was inadvertently planted in the southern Willamette Valley (at least in residential settings) as it accidentally got into the native nursery trade.

Sulfur Cinquefoil (Potentilla recta) Identification and Control 2 Bruce Newhouse Eugene

June 5, 2014 – Nathan Johnson (Center for Natural Lands Management)

Thanks for the identification hints... for me it’s pretty easy to distinguish between the two potentillas this time of year. It is much harder early in the season before the P. recta begins to bolt.

For control we spend lots of labor-intensive man hours surveying to locate new, small populations, and retreat known populations from previous years. I can't stress the importance of surveying enough... the harder we look, the more we find both at small scales (finding small plants) and large scales (finding previously unknown populations).

When we find plants we typically treat with 0.5% Milestone or 2-3% Garlon 3a together with 0.25% nufilm and 1% marking dye.

Nathan Johnson Invasive Species Project Manager Center for Natural Lands Management

June 5, 2014 – Dave Wilderman (Washington Department of Natural Resources)

Thanks Nathan, we have this on one of our sites as well. What are you using to control it?

Also, a few other notes on distinguishing P. recta from P. gracilis. Flower color: P. recta has pale yellow flowers vs. P. gracilis bright, saturated yellow. Leaves: P. recta holds its leaves more erect and in more of a vertical plane, i.e. they are somewhat tilted sidewise rather than being held flat. Flower bracts: these are bracts attached just below the sepals. On P. recta, the bracts are similar in length to the sepals, while in P. gracilis they are noticeably smaller than sepals. This last feature is just something I’ve observed myself, not read about. But I’ve seen this both in eastern WA and here in Thurston county, and it appears consistent and is a useful character when plants are in bud or past flower.

David Wilderman Natural Areas Program Ecologist Washington State Department of Natural Resources

June 5, 2014 – Steve Erickson

One other ID tip. The seeds of P. recta have a reticulate surface. That is, they look like their covered with a network of veins. Its very distinct. P. gracillis and P. glandulosa have smooth seed surfaces.

Steve Erickson

June 5, 2014 – Rod Gilbert (Joint Base Lewis-McChord)

Sulfur Cinquefoil (Potentilla recta) Identification and Control 3

One other important thing to remember if you do have this on your land is that you have to pull flower heads before spraying if it's in flower, as they will go on to set viable seed regardless of which herbicide is used. Using a GPS to record the location accurately will allow you to find it in early spring when they are still germinants and easily controlled.

Rod Gilbert Fish and Wildlife Program (Versar Inc) Joint Base Lewis-McChord

Sulfur Cinquefoil (Potentilla recta) Identification and Control 4 Sulfur Cinquefoil Identification Additional comparison photos

Photos credit Bruce Newhouse with permission. See more of his photos of Potentilla recta and Potentilla gracilis at http://brucen.zenfolio.com/p766205970.

Comparison of flowers between the two plants.

Comparison of the back of the flowers and the flower bracts.

Sulfur Cinquefoil (Potentilla recta) Identification and Control 5